Intermittent Microwave Drying of Apple Slices: Drying Kinetics, Modeling, Rehydration Ratio and Effective Moisture Diffusivity

Abstract

In this research, thin layer drying characteristics, rehydration ratio and effective moisture diffusivity of apple were investigated using microwave dryer which has intermittent and continuous modes. Drying time varied between 25 and 215 minutes and they declined with the rise in microwave power and reduction in pulsing ratio. In an attempt to pick the optimum thin layer models for the drying applications, 8 mathematical models suited to the experimental results. On the grounds of the statistical tests evaluation, Midilli et al model which represent drying characteristics are optimally suited than other models. The highest rehydration ratio was recorded for the samples dried at 100W continuous mode and the lowest ratio at 300W continuous application. Effective moisture diffusivity values were computed by the 2 nd law of Fick and changing between 3.04x10-9 and 2.53x10-8 m 2 s-1. Consequently, the intermittent microwave method could be used as a favorable drying method for obtaining high-quality fruit slices or processing valuable material and continuous microwave drying can be taken as another drying approach for apple samples.

Farklı Sıcaklık ve Mikrodalga Güçlerinde Kurutulan Elma Dilimlerinin Kurutma Özellikleri

“…Bu durum, yüksek mikrodalga güçlerinde su moleküllerinde daha fazla ısınma ile açıklanabilir. İzli ve Polat [40] farklı mikrodalga güçlerinde kurutulmuş elma dilimlerinde Deff değerlerini, 8.11 × 10 −9 ile 1.22 × 10 −8 m 2 s −1 arasında gözlemlemişlerdir. Deff değerleri Mikrodalga güçlerinin 100 W'dan 300 W'a artmasıyla artmıştır.…”

“…Sıcaklı artışı elma örneklerinin Deff değerini önemli ölçüde artırmıştır. Yapılan çalışma ile elde edilen Deff değeri, elma dilimleri üzerine yapılan iki farklı çalışmadaki Deff değerleri ile (7.03×10 −10 −1.08×10 −9 m 2 s −1 ) [44] ve (2.27×10 −10 −4.97×10 −10 m 2 s −1 ) [40] benzer sonuçlar elde edilmiştir. Elma dilimleri ve elma posası ile yapılan iki farklı çalışmadaki Deff değerleri ise sırasıyla 1.79×10 −9 −4.45×10 −9 m 2 s −1 [45] ve 1.9082×10 −9 −3.9346×10 −9 m 2 s −1 [46] bulunmuş ve elde ettiğimiz Deff değerlerinden biraz daha düşük bulunmuştur.…”

Convective Drying of Apple Enhanced with Microwaves and Ultrasound—Process Kinetics, Energy Consumption, and Product Quality Approach

“…However, continuous microwave drying may cause overheating and deterioration of the quality of the dried material. This can be overcome, for example, by intermittent microwave-convection drying [5]. Another disadvantage of using microwaves is uneven heating due to the standing wave pattern.…”

Volatile compounds, bioactive properties and chlorophylls contents in dried spearmint (Mentha spicata L.) as affected by different drying method

“…The qualitative and quantitative composition of these compounds are affected by pre-and post-harvest conditions (Nalawade et al 2019). Drying processes particularly change the profile of VC depending on temperature, humidity and time conditions (Korkmaz et al 2020;İzli & Polat 2020;Polat et al 2021). Nowadays, the content of bioactive substances in herbs and spices has been considered as another parameter of their quality, with a rising trend (Uribe et al 2016).…”